/*
** $Id: lparser.h,v 1.76.1.1 2017/04/19 17:20:42 roberto Exp $
** Lua Parser
** See Copyright Notice in lua.h
*/

#ifndef lparser_h
#define lparser_h

#include "llimits.h"
#include "lobject.h"
#include "lzio.h"

/*
** Expression and variable descriptor.
** Code generation for variables and expressions can be delayed to allow
** optimizations; An 'expdesc' structure describes a potentially-delayed
** variable/expression. It has a description of its "main" value plus a
** list of conditional jumps that can also produce its value (generated
** by short-circuit operators 'and'/'or').
*/

/* kinds of variables/expressions */
typedef enum
{
    VVOID,      /* when 'expdesc' describes the last expression a list,
             this kind means an empty list (so, no expression) */
    VNIL,       /* constant nil */
    VTRUE,      /* constant true */
    VFALSE,     /* constant false */
    VK,         /* constant in 'k'; info = index of constant in 'k' */
    VKFLT,      /* floating constant; nval = numerical float value */
    VKINT,      /* integer constant; nval = numerical integer value */
    VNONRELOC,  /* expression has its value in a fixed register;
                 info = result register */
    VLOCAL,     /* local variable; info = local register */
    VUPVAL,     /* upvalue variable; info = index of upvalue in 'upvalues' */
    VINDEXED,   /* indexed variable;
                ind.vt = whether 't' is register or upvalue;
                ind.t = table register or upvalue;
                ind.idx = key's R/K index */
    VJMP,       /* expression is a test/comparison;
            info = pc of corresponding jump instruction */
    VRELOCABLE, /* expression can put result in any register;
                  info = instruction pc */
    VCALL,      /* expression is a function call; info = instruction pc */
    VVARARG     /* vararg expression; info = instruction pc */
} expkind;

#define vkisvar(k) (VLOCAL <= (k) && (k) <= VINDEXED)
#define vkisinreg(k) ((k) == VNONRELOC || (k) == VLOCAL)

typedef struct expdesc
{
    expkind k;
    union
    {
        lua_Integer ival; /* for VKINT */
        lua_Number nval;  /* for VKFLT */
        int info;         /* for generic use */
        struct
        {               /* for indexed variables (VINDEXED) */
            short idx;  /* index (R/K) */
            lu_byte t;  /* table (register or upvalue) */
            lu_byte vt; /* whether 't' is register (VLOCAL) or upvalue (VUPVAL) */
        } ind;
    } u;
    int t; /* patch list of 'exit when true' */
    int f; /* patch list of 'exit when false' */
} expdesc;

/* description of active local variable */
typedef struct Vardesc
{
    short idx; /* variable index in stack */
} Vardesc;

/* description of pending goto statements and label statements */
typedef struct Labeldesc
{
    TString* name;   /* label identifier */
    int pc;          /* position in code */
    int line;        /* line where it appeared */
    lu_byte nactvar; /* local level where it appears in current block */
} Labeldesc;

/* list of labels or gotos */
typedef struct Labellist
{
    Labeldesc* arr; /* array */
    int n;          /* number of entries in use */
    int size;       /* array size */
} Labellist;

/* dynamic structures used by the parser */
typedef struct Dyndata
{
    struct
    { /* list of active local variables */
        Vardesc* arr;
        int n;
        int size;
    } actvar;
    Labellist gt;    /* list of pending gotos */
    Labellist label; /* list of active labels */
} Dyndata;

/* control of blocks */
struct BlockCnt; /* defined in lparser.c */

/* state needed to generate code for a given function */
typedef struct FuncState
{
    Proto* f;               /* current function header */
    struct FuncState* prev; /* enclosing function */
    struct LexState* ls;    /* lexical state */
    struct BlockCnt* bl;    /* chain of current blocks */
    int pc;                 /* next position to code (equivalent to 'ncode') */
    int lasttarget;         /* 'label' of last 'jump label' */
    int jpc;                /* list of pending jumps to 'pc' */
    int nk;                 /* number of elements in 'k' */
    int np;                 /* number of elements in 'p' */
    int firstlocal;         /* index of first local var (in Dyndata array) */
    short nlocvars;         /* number of elements in 'f->locvars' */
    lu_byte nactvar;        /* number of active local variables */
    lu_byte nups;           /* number of upvalues */
    lu_byte freereg;        /* first free register */
} FuncState;

LUAI_FUNC LClosure* luaY_parser(lua_State* L, ZIO* z, Mbuffer* buff, Dyndata* dyd, const char* name, int firstchar);

#endif
